Creates a modifiable clone of the Freezable, making deep copies of the object's values. When copying the object's dependency properties, this method copies expressions (which might no longer resolve) but not animations or their current values. (Inherited from Freezable.)

Coerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject. (Inherited from DependencyObject.)

Ensures that the Freezable is being accessed from a valid thread. Inheritors of Freezable must call this method at the beginning of any API that reads data members that are not dependency properties. (Inherited from Freezable.)

Raises the Changed event for the Freezable and invokes its OnChanged method. Classes that derive from Freezable should call this method at the end of any API that modifies class members that are not stored as dependency properties. (Inherited from Freezable.)

Verifies that the Freezable is not frozen and that it is being accessed from a valid threading context. Freezable inheritors should call this method at the beginning of any API that writes to data members that are not dependency properties. (Inherited from Freezable.)

The TaskbarItemInfo class provides a managed wrapper for Windows 7 taskbar functionality. For more information about the Windows shell and native taskbar APIs, see Taskbar Extensions. TaskbarItemInfo is exposed as the Window::TaskbarItemInfo dependency property on a Window.

The Windows 7 taskbar provides enhanced functionality that enables you to use the taskbar item to communicate status to a user and expose common tasks when the window is minimized or hidden. The functionality that is exposed by the TaskbarItemInfo class is unavailable in versions of Windows earlier than Windows 7. Applications that use the TaskbarItemInfo class can still run in earlier versions of Windows; however, these taskbar enhancements are unavailable in the earlier versions.

In Windows 7, some taskbar functionality might be unavailable, depending on the user's settings. For example, taskbar functionality is unavailable if Windows Aero is disabled or if the application is started with elevated permissions. Your application should provide other ways to interact with the user that do not depend on the enhanced taskbar functionality in Windows 7.

Program icons in the notification area, which is at the far right of the taskbar, are typically used to communicate application status to a user. By default, the Windows 7 taskbar hides program icons in the notification area. However, you can set the Overlay property to add an image to the taskbar button to communicate status, such as online status in a messaging application. The overlay image lets users see the application status even if they cannot see the program icon in the notification area. You can also display the progress of running tasks in the taskbar button by setting the ProgressState and ProgressValue properties.

The Windows 7 taskbar displays a thumbnail of the application when you move the mouse pointer over the taskbar button. By default the whole application window is shown. You can specify a particular part of the window to display in the thumbnail by setting the ThumbnailClipMargin property. You can also specify a Description that is displayed in a tooltip above the taskbar thumbnail. The tooltip is displayed even when the thumbnail cannot be seen because of user settings.

You can add buttons to the taskbar thumbnail to provide access to common tasks without switching to the application window. For example, Window Media Player provides Play, Pause, Forward, and Back buttons that let you control media playback from the taskbar thumbnail when the application is minimized. Buttons in the taskbar thumbnail are represented by ThumbButtonInfo objects and are contained in the ThumbButtonInfos collection.

The following illustration shows the enhanced features of the Windows 7 taskbar.

The following example shows how to create a TaskbarItemInfo in markup. The TaskbarItemInfo contains a collection of ThumbButtonInfo objects that provide access to the Play and Stop commands from the taskbar item.

The following markup and code shows the previous example in its full context. The application uses a BackgroundWorker to count from 0 to 100 and displays its progress in the user interface. The task can be started and stopped from the taskbar preview. The progress is displayed in the taskbar button.